Multiple Input Multiple Output (MIMO) increases the efficiency of data transmission and reception using multiple transmit antennas and multiple receive antennas. A receiver receives data through multiple paths when multiple antennas are used, whereas the receiver receives data through a single antenna path when a single antenna is used. Accordingly, MIMO can increase data transmission rate and throughput while also improving coverage.
To increase multiplexing gain of MIMO, channel status information (CSI) can be fed back from a MIMO receiver to be used at a MIMO transmitter. The receiver can determine the CSI by performing channel measurement using a predetermined reference signal (RS) from the transmitter.